Fulvio Giudici

L’articolo completo (in francese) è stato pubblicato nella rivista forestale svizzera nel 2021 (Cioldi, F.; Conedera, M.; Giudici, F.; Herold, A., (2021). Dynamique évolutive de la forêt au Sud des Alpes suisses. Schweizerische Zeitschrift für Forstwesen, 172 (5), 318-329. doi: 10.3188/szf.2021.0318)

La surface forestière du Sud des Alpes suisses a plus que doublé en 120 ans, avec une accélération importante de cette croissance après la Seconde Guerre mondiale. En utilisant les données de l’Inventaire forestier national (IFN), l’article décrit la structure, la composition et l’évolution des forêts de cette région, en distinguant les forêts établies avant 1940, celles formées entre 1940 et 1985, ainsi que celles établies après 1985. En raison de difficultés structurelles et environnementales, la forêt a évolué de manière naturelle depuis plusieurs décennies sans véritable gestion régulière. Cette évolution conduit au vieillissement progressif des forêts de plus en plus denses et sombres, qui finit par favoriser les essences intermédiaires et surtout finales, en particulier le hêtre. Les espèces pionnières, en revanche, sont en fort déclin dans les forêts établies depuis longtemps et pour elles – le bouleau et le mélèze en particulier – les zones boisées de formation récente représentent un refuge important. En outre, les analyses mettent en évidence la rareté de la régénération, particulièrement importante pour garantir la stabilité des forêts à moyen et long terme, mais elles montrent aussi l’effet bénéfique des interventions sylvicoles sur l’abondance du rajeunissement. Les extrêmes climatiques, en particulier les sécheresses de plus en plus fréquentes, intensifient encore la concurrence entre les espèces. Dans ce cadre, le châtaignier – essence symbolique du Sud des Alpes – est en grande difficulté, surtout dans les stations fortement exposées au soleil et à la pénurie d’eau. Les résultats de l’IFN montrent effectivement une forte mortalité du châtaignier au cours des trois dernières décennies.

Rhizosphere respiration is a significant component of the total carbon dioxide (CO₂) efflux from forest soils. Since the root-derived CO₂, is not part of soil C loss, it is worth estimating this fraction and determining its driving forces. In order to determine the dependency of the root respiration on recent photosynthates in a European chestnut (Castanea sativa Mill.) stand in Southern Switzerland, we girdled 104 tree stems on an area of 625 m² at the end of August. The response of forest girdling on the below-ground C cycle was assessed by measuring soil respiration, soil microbial carbon biomass and root composition during the 37 days of experiment.
Recent photosynthates contributed significantly to the soil respiration, which declined by 22 and up to 36% on average after girdling. The difference in soil respiration between girdled and control plots was significant only during a short time period (9-20 days after girdling). A significant decline in soil respiration was observed up to a distance of 4 in from the stems. Fine roots from girdled trees were strongly depleted in starch (-90%), although they were functional as shown by the dehydrogenase test. We assume that a large fraction of the starch loss was most likely respired and contributed to the soil respiration or there was a decline in new starch supply due to reduced carbon allocation to the roots.

Das Kastanienprogramm ist ein Gemeinschaftsprojekt der Waldwachstumsforschung der WSL, Forschungsgruppe Waldentwicklung, und der WSL Sottostazione Sud delle Alpi. Es ist Teil des Konzeptes «Probleme der Kastanienstufe» (Kastanienprogramm). Das Projekt ist mit anderen laufenden und geplanten Projekten eng verbunden, die verschiedene Aspekte der Ökologie und der Bewirtschaftung der Kastanie berücksichtigen. Von den zahlreichen Fragen und Aspekten der Kastanienwirtschaft im weitesten Sinne untersucht das Projekt einen Teil: den Anfang einer Produktionskette «Kastanienholz».

This contribution presents results of a 3 year project on chestnut (Castanea sativa Mill.) ring shake (RS). The main objective was the examination of the relationships between radial wood cohesion, growth stresses and RS occurrence. Investigative studies were carried out on wood material collected in chestnut coppice forests from the southern part of the Swiss Alps. Analyses were performed on the basis of a comparison of wood with and without RS. Anatomical investigations of the RS privileged plane of fracture (earlywood area) showed that ring shaken wood displays a higher amount of rays and smaller earlywood vessel lumina. Mechanical rupture testing revealed that earlywood radial split resistance is positively correlated with ring width. Examination of longitudinal strain-induced displacement performed on the stem surface of standing coppice trees did not reveal the existence of a direct relationship between high stress level and RS occurrence. Consequently it has been highlighted that the principal cause of RS in chestnut is associated with the unbalance between the weak structure of the tangential wood plane and the release of growth stresses. Stress overloaded trees react by producing a strengthened wood. However when trees are cut, as a consequence of the relieving of high growth stresses, mechanically originated RS are developed. Nevertheless mechanical testing proved that not all trees are prone to RS in the same way, what offers the forest manager the opportunity to operate in order to reduce the risk of RS.

Management of chestnut crops has to deal with two different concepts which are defined by two different goals: timber production and fruit production. Timber production may be reached with two different management methods: coppice and high forests. Timber producing chestnut forests in Europe are generally managed by the coppice system. Otherwise, fruit production systems may be considered as orchards, although in some countries they are considered as forests. To deal with the different aims it is necessary to be clear i) about the production goal, ii) about the management system. While timber production with chestnut high forest may be described and defined with the traditional and international widely accepted silvicultural terminology and definitions, this is not the case for coppice forests and orchards. Therefore the aim of this paper (elaborated by the working group "Silviculture" during the COST Action G4 - Multidisciplinary Research on Chestnut) is to compile a document as a reference and as a work instrument for research and management activities in chestnut forests in order to ensure an efficient exchange and comparison of scientific data and information and to promote the dissemination of the research results to the end users.

To study the sprouting ability of chestnut stands a 60 year old coppice stand in southern Switzerland was coppiced by removing all live and dead shoots. Two years and four years after coppicing surveys of the newly produced shoots was carried out in order to analyse growth and mortality of the young stand and to verify the factors influencing the sprouting ability. The mortality of stools was only 4%; the number of produced shoots was, with 48 shoots per stool, high and the growth of the shoots was remarkable. Stand structure, stool density and the dimensions of the old stools neither reduced sprouting ability nor influenced the diameter and height growth, but the stump cut quality has a positive effect. Finally, height measurement of the dominant shoot on a stool provides a good indicator for the evaluation of the vigour of the regeneration in a chestnut coppice.

L'articolo presenta irisùltati di uno studio eseguito presso la Cattedra di Politica e Economia Forestale del Politecnico di Zurigo. Lo-Scopo di questo lavoro di ricerca era di offrire una panoramica della situazione attuale dei Patriziati ticinesi. In particolare si sono analizzate le strutture e l'organizzazione, valutando il ruolo e le attività dei Patriziati sulla base dì alcuni esempi concreti e rivolgendo particolare attenzione aila gestione dei boschi ed ai problemi connessi.

No official and coherent data on the distribution of the European chestnut exist despite its wide range of distribution and the important economic role it has played in many countries. In 1997, in the framework of the COST action G4 “Multidisciplinary Chestnut Research”, quantitative and qualitative data on chestnut forests were collected, mostly from the National Forest Inventories, in order to provide as sound a picture as possible of this important European resource. A total of 2.25 million hectares of forest dominated by chestnut were recorded, with 1.78 million hectares (79.0 %) cultivated for wood and 0.43 million hectares (19.3 %) for fruit production. The remaining 0.04 million hectares (1.7 %) were classified as irregular structures or without any indication. A further 0.31 million hectares are thought to be mixed forest with chestnut.
Three types of chestnut countries can be distinguished : (i) countries with a strong chestnut tradition (e.g. Italy, France, southern Switzerland, Spain, Portugal and Greece), where the chestnut stands are cultivated with intensive and characteristic silvicultural systems (coppices and orchards) ; (ii) countries with only a partially developed chestnut tradition due to the country’s particular geography (e.g. England) or history (e.g. Croatia, Turkey, Georgia) ; (iii) countries where the chestnut only sporadically occurs (e.g. Hungary, Bulgaria, Belgium) or has been recently introduced (e.g. Slovakia, Netherlands).
A comparison of the present distribution of traditional silvicultural systems and historical data on chestnut distribution supports the hypothesis that the large-scale chestnut forest plantations are of post-Roman origin. Chestnut cultivation is now at a turning point as the changed needs of society have changed as it has moved away from a rural-based to an industrial and urban-oriented organization. The evolution of the chestnut market in recent decades confirms the potential of this resource for both traditional products and new services and goods related to organic-food and environmentally friendly products.

Il presente contributo riporta i risultati di una ricerca eseguita dalla Sottostazione Sud delle Alpi di Bellinzona dell'Istituto WSL in collaborazione con la Cattedra di Politica e Economia Forestale del Politecnico di Zurigo. Obiettivo dello studio era di fornire alcuni spunti di riflessione sulla situazione attuale dei Patriziati ticinesi sulla base dell'analisi di alcuni casi concreti.
Dopo aver presentato le strutture e l'organizzazione dei Patriziati considerati,vengono esaminate le attività svolte ed in particolare i problemi legati alla gestione dei boschi e del territorio in generale.

La Sottostazione Sud delle Alpi di Bellinzona è una delle due stazioni esterne del WSL, istituto del settore dei Politecnici federali che si occupa di ricerca ambientale. Creata all'inizio degli anni '90, la Sottostazione svolge studi su argomenti e problemi specifici del territorio e degli ecosistemi terrestri della regione Sudalpina.

I parametri strutturali, della rinnovazione e di qualità dei fusti sono stati analizzati in due boschi di betulla con più popolamenti di età compresa tra 25 e 40 anni. Obiettivo del lavoro era la valutazione delle potenzialità produttive e delle esigenze selvicolturali in boschi di neoformazione di betulla ad evoluzione naturale. I popolamenti puri sono risultati differenti da quelli misti solo per alcune caratteristiche (altezze dominante e relative lunghezze e forma delle chiome, presenza di altre specie nella rinnovazione naturale). Le provvigioni riscontrate si aggirano intorno a 150-300 m3ha- 1 e gli incrementi medi intorno a 5-7 m3.ha- 1.anno- 1. L'assenza di interventi selvicolturali precedenti spiega l'elevato numero di alberi ad ettaro (tra 900 e 1.500), e la conseguente relativamente scarsa presenza di rinnovazione di betulla. Le caratteristiche di rettilineità e di inclinazione dei fusti permettono di ipotizzare il loro utilizzo anche per produrre assortimenti di pregio.

Structural parameters, natural regeneration and stem quality have been studied in two birch stands with trees 25-40 years old. Goal of this work was the valuation of productive potentiality and silvicultural problems in birch secondary succession forests with complete natural evolution. Pure stands result different from the mixed ones only for few features (dominant high and crown form and length, number of species in regeneration phase). Growing stocks are about 150-300 m3 ha-land mean annual increment is 5-7 m3 ha-1 anno - 1. The Jack of tending in the past can explain both the high number of trees per hectare (900-1.500) and the relative lack of natural regeneration of the birch. Stem straight and inclination allow to assume their utilisation for high quality timber assortments.

Cet article décrit le système d'exploitation semi-mécanisé qui fut adopté sur deux surfaces de coupe dans la commune de Novaggio. Il présente une analyse des différentes opérations, un examen des coûts et des rendements. Enfin, il relate aussi les expériences acquises, notamment dans la production de copeaux.

Dans le numéro 5 de La Forêt, nous avons traité de «L'exploitation semi-mécanisée dans un taillis de châtaignier». Une erreur s'étant glissée dans la légende d'une photo (en haut de la page 24), le lecteur aurait pu se faire une idée plutôt fausse de cette technique: soit parce que cette illustration donnait l'impression qu'on laisse beaucoup de bois en forêt, mais aussi parce qu'on ne voyait guère sur la photo de régénération naturelle.
Ce deuxième article nous donne l'occasion de transmettre quelques autres informations sur ce type de forêt. Il nous permet aussi de revenir sur la façon de la gérer au moyen de techniques sylvicoles (les coupes de taillis qui sont souvent considérées, à tort, comme des «coupes rases»). Ce thème est particulièrement d'actualité à l'heure où les discussions sur la nécessité de rationaliser les exploitations forestières vont bon train.

La Sottostazione Sud delle Alpi è una delle due stazioni esterne del WSL, istituto di ricerca del settore dei Politecnici federali che si occupa di Foresta, Neve e Paesaggio. Creata all'inizio degli anni '90 la Sottostazione svolge studi su argomenti e problemi specifici del territorio e dei boschi della regione Sudalpina.